The present invention relates to a method for manufacturing a low density foamed body containing rubber as a main constituent.
A conventional method for manufacturing foamed rubber is known according to which a mixture containing rubber, a foaming agent, and a crosslinking agent is fed into a mold, the mold is heated to foam the mixture, and the produced foamed body is released from the mold. However, with a foamed body manufactured according to this method, an expansion ratio of only about 3 to 6 and a density of about 0.15 to 0.3 are obtainable. It has thus been difficult with this method to either increase the expansion ratio or two decrease the density. When the foaming agent is used in a great amount to raise the expansion ratio, the foaming pressure within the mold rises excessively when the mold is heated. Then, when the mold is opened, the foamed body immediately expands, explodes, and is scattered away.